This is a national collaborative randomized clinical trail to test the efficacy of the use of photocoagulation to obliterate parafoveal neovascular membranes in patients with senile macular degeneration, presumed ocular histoplasmosis, or idiopathic neovascularization. Twelve clinical centers throughout the United States are recruiting patients, who are randomly assigned to either photocoagulation therapy or careful follow-up without photocoagulation. Twelve-hundred patients will be recruited over a three-year period.